In "Twister," the movie opening today, stars Helen Hunt and Bill Paxton stand in an Oklahoma cornfield. Wind whips their hair back and debris flies toward them as the husband and wife tornado chasers, eyes keen, look in awe at a monstrous, growling, oncom ing tornado.

"My God," they say.

In a preview screening Wednesday, two real husband and wife tornado chasers, meteorologists Richard and Daphne Thompson of Kansas City, were saying practically the same thing:

My... What a bunch of hooey.

It's not that the young chasers thought "Twister" was bad. Not at all. The special effects that created the tornadoes were great.

"The effects were better than I thought for the tornadoes," Richard Thompson said.

And in terms of excitement, Daphne Thompson, 23, who's an Internet WebMaster for the National Weather Service, and Richard Thompson, 29, who tracks storms for the National Storm Prediction Center, thought it was pretty intense, maybe ranking an F3 on the F0 to F5 tornado intensity scale.

But as for capturing tornado chasing -- or even to the physics of real tornadoes -- well, as Fred Ostby, chief forecaster for the Storm Prediction Center, said after the movie, "I thought `E.T.' was more believable."

Consider:

1. In a real twister, air and debris whooshes in toward the tornado, not out, with debris, 18-wheel oil trucks, farm equipment, cows and houses being flung away. At the least, the stars' hair should have been blowing forward, not back.

2. Lightning and thunder? Check your physics books, Steven Spielberg (producer of the Warner Brothers film). They don't flash and crash at the same time. Light travels faster than sound, so lightning is seen before thunder is heard unless a storm is di rectly overhead.

3. Yes, tornadoes wander, alter their path and change in intensity, but they don't skitter back and forth across roads like jittery rabbits, take sudden U-turns or drop out of sunny and virtually windless skies.

Storms just don't move east, then west, then stop. "That's wrong," Richard Thompson said. They have relatively distinct paths.

4. Chasers don't check radar and whoop "Whooeee! We've got ourselves an F3!" as the movie suggests.

Meteorologists do use the Fujita-Pearson Tornado Intensity Scale to rate the power of tornadoes, from F0 (weak with light damage) to F5 (violent with incredible damage). "But we only determine the intensity rating after we look at the damage," Daphne Thompson said. "We can't look at it on Doppler radar and say, `Yes, this is an F3.' "

For instance, only after meteorologists viewed damage from the Hesston, Kan., tornado of 1990 and the Andover tornado of 1991 were they rated at F5 intensity.

Of course, moviegoers might call this nitpicking. But Ostby and the Thompsons say there's much more. For example, one town in the movie is hit without warning, on TV or otherwise.

"That would never happen," Ostby said. "One thing they seemed to have totally ignored is the tornado spotters."

Cloud formations also are wrong. And in the movie, storm predictions are constantly being fed from the National Severe Storms Laboratory in Oklahoma, while it's really the Storm Prediction Center in Kansas City that predicts tornadoes. The lab does bas ic research.

In addition, the movie's "new" tornado-predicting technology, which is dubbed "Dorothy" and contains hundreds of tiny plastic sensors to ride up the funnel to feed back data, isn't new. It's based on technology the weather service abandoned 10 years a go.

"Anyway, those little tiny plastic sensors would have been shattered by the big boards that were flying through the air," Daphne Thompson said.

Today, she said, chasers use "Turtles," squat sensor packs placed in the middle of roads every few hundred yards. They hope they have predicted the tornado's path well enough that the twister will pass right over the devices.

Which raises the final point:

Chasers don't get in the way of tornadoes, let alone drive a speeding van or stand 50 yards from one, as happens time and again in the movie.

"It's insane. Just absolutely unbelievably insane," said Richard Thompson, who has chased down 40 to 50 tornadoes. Daphne Thompson has chased about 30.

"You would never even consider living through what they did," he said. "If it was close to real life, you'd be dead in the first 15 minutes of the movie."

In "Twister," Paxton and Hunt drive at more than 80 mph only feet away and directly parallel to a twister. When the tornado suddenly turns, they ram their car into a bridge abutment and hold on for dear life as the tornado, spitting debris, passes over them.

"I hope people aren't thinking that that's what we do," Richard Thompson said. "No one in their right mind would try to do that."

Of course, when it comes to scientific or historical accuracy, Hollywood has never pretended to be faithful. What did it matter, for example, that in the movie "Jurassic Park," all the dinosaurs came from the Triassic period?

The truth about chasing tornadoes, Ostby said, is that even with the best predictive equipment and training, it's still a matter of luck, timing and patience. The Thompsons sometimes drive 14 hours and hundreds of miles to be where they think a tornado might develop, but then come up empty.

"You can easily go out for a week and have nothing happen," Ostby said.

The Thompsons hope the public understands that. Because if they have any fears about "Twister," it's that the movie will spawn a migration by would-be tornado chasers who hope to capture some of the movie drama, just as shark hunters took to the seas a fter the movie "Jaws."

Already these days, real chasers have to contend with news crews and thrill-seekers clogging roads on their way to capture footage of tornadoes. With this movie, they can envision a bad situation getting worse. Richard Thompson recalls a set of 1991 st orms in Oklahoma that drew a caravan 100 cars long.

"It was that bad," he said.

And that potentially dangerous: Although the vast majority of tornadoes cause little or no damage, they still can be deadly.

Tornadoes killed 29 persons in 1995 and 19 so far this year. The height of tornado season, in which two-thirds of tornadoes occur, runs from April through June. It's only half over.

If there is one thing the tornado chasers liked about "Twister," it's that the movie also depicts the fierce force of the winds, obliterating barns, houses, even causing several deaths.

"We hope the movie will discourage people from chasing," Daphne Thompson said. "We hope it'll show it as scary enough to say, `A tornado is not something I want to encounter.' We don't want a lot of people out on the road who don't know what they're do ing."